The Human Breast Tissue and Pathology Core (HBTPC) resource provides essential services to all projects in the Johns Hopkins Breast Cancer SPORE in three major areas: tissue acquisition and processing, tissue histology and analysis, and pathologist consultation. As an integral component of our Breast Cancer Program, this Core also provides these services in collaboration with investigators of other SPORE programs, other breast cancer research programs at Johns Hopkins'Sidney Kimmel Comprehensive Cancer Center (SKCCC), and a number of collaborating investigators at other institutions. It is therefore a unique and essential resource. For tissue acquisition and processing, the HBTPC oversees the collection and distribution of fresh and freshfrozen specimens, including samples of invasive carcinoma, in situ carcinoma, metastatic carcinoma, and normal breast from breast cancer patients and from healthy (breast reduction) patients. In addition to prospective collection, the HBTBC has reviewed and catalogued similar specimens that had been collected prior to the SPORE funding and stored in the Pathology Department tissue bank, providing a resource of over 1200 frozen samples. The HBTPC continuously addresses needs of specific projects in the Breast SPORE program, by initiating collection and distribution of peripheral blood and duct lavage specimens, establishing explants for ex vivo testing of novel therapeutic agents, constructing tissue arrays that represent the full spectrum of neoplasia of the breast, and overseeing an immediate autopsy program that harvests tissues from widely metastatic, advanced cancers. For tissue histology, the HBPTC utilizes the existing Reference Histology and Immunohistochemistry laboratories in the Department of Pathology. The Core also uses a tissue microarray laboratory in Pathology and laser microdissection equipment in the Cancer Center, providing these services in an integrated, cost-effective manner. Perhaps the most important contribution of this Core to the Program is that of expert pathologist consultative services. Two pathologists, experienced in both the disciplines of surgical pathology and breast cancer research, work closely with SPORE investigators in experimental design, use of human tissues, and interpretation of data involving analysis of human tissues. These investigators (Drs. Argani and Gabrielson) have co-authored 43 breast cancer publications during the five years of SPORE funding, reflecting their engagement in the program and the contribution of this core to breast cancer research at Johns Hopkins.